gcc/testsuite/gcc.dg/torture/pr52244.c

/* { dg-do run } */

extern void abort (void);

typedef union u_r 
{
  _Bool b;
  unsigned char c;
} u_t;

u_t
bar (void)
{
  u_t u;
  u.c = 0x12;
  return u;
}

u_t  __attribute__ ((noinline))
foo (void)
{
  u_t u;

  u.b = 1;
  u = bar ();

  return u;
}

int main (int argc, char **argv)
{
  u_t u = foo ();
  if (u.c != 0x12)
    abort ();
  return 0;
}